Reaction Torque Transducers

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Reaction Torque Transducers

When you choose a reaction torque transducer from S. Himmelstein and Company, you get ultimate real-world accuracy based on 50+ years of experience and innovation.

A reaction torque transducer measures torque transferred to ground (or any rigid structural member). While intended primarily for static torque measurement, these reaction transducers can also measure dynamic torque, thanks to Newton’s third law of motion. (For every action there is an equal and opposite reaction.)

Reaction Torque Transducer Principles

A reaction transducer has two mounting flanges. One face is fixed to ground or a rigid structural member and the other to the rotating or rotary element. Rotation generates shear forces between the flanges. S. Himmelstein and Company measures these forces with precision strain gages. These incorporate wire that responds to being stretched or compressed with strand small changes in electrical resistance. While the change is subtle, it can be detected effectively by incorporating four gages into a Wheatstone Bridge arrangement.

Accurate and repeatable torque measurement is achieved through precise manufacture and installation of the strain gages — plus temperature compensation and sophisticated signal conditioning. Details vary by transducer size and type, but strain gages are typically arranged at 45 degrees to the rotation axis. In this configuration, the shear stress produced by twisting creates tensile and compressive stresses of equal magnitude.

When selecting a reaction torque transducer, always consider the extraneous loads to which it will be subjected. Typical of such loads are bending moments and axial thrust. Transducer specifications list the maximum such loads that can be safely applied.


Electrical resistance varies with temperature. Without compensation, the result would be inaccurate readings. While strain gages are temperature-compensated, reaction torque sensors incorporate our superior technology for improved accuracy.

Common Applications for Reaction Transducers

Torque measurement is widely used in process control and testing. It can yield valuable information about how a process is running and enable torque control that improves product consistency. In testing, torque measurement can indicate product performance, safe operating limits, maximum loads and breaking points.

Coil winding systems like those used in steel and paper manufacture are a common torque measurement application. In rolling mills, it can indicate load and hence material properties. In chemical processing, a change in fluid viscosity can signal the onset of a chemical reaction or degree of mixing.

In test and measurement, torque measurement is used to calibrate torque wrenches, determine fastener breaking torque and monitor the force needed to open child-proof containers. Torque can even indicate the approach of plastic deformation in materials testing.

Types of Reaction Torque Transducers

We offer four types:

  • Hollow Flanged Transducer — Achieve faster response by employing a patented double-wall design that results in a compact package with high torsional stiffness. Maximum loads range from 60 to 2,400,000 lbf-in.
  • Solid Flanged — Handle torques from 10 ozf-in to 750,000 lbf-in. Overload capacity is twice the rated torque.
  • C-Faced Hollow Flange — Mate with NEMA C-Face motors and offer high accuracy and stiffness along with low deflection. Handle torque from 50 to 20,000 lbf-in.
  • Square Drive — Low weight and compact size simplify installation and handling. They are intended for larger torques, in the 300,000 to 4,000,000 lbf-in range.

Experienced and Professional

S. Himmelstein and Company has been in the torque measurement business since 1960. We're known for building high-quality torque measurement transducers that are easy to install and use and that deliver years of dependable service. Our after-sales service and support is second-to-none. Further, our highly skilled employees take pride in building the best products available at their price point. Contact us today to learn more.